On 1/15/20 1:36 PM, Damien Hedde wrote:
In qdev_set_parent_bus(), when changing the parent bus of a
realized device, if the source and destination buses are not in the
same reset state, some adaptations are required. This patch adds
needed call to resettable_change_parent() to make sure a device reset
state stays coherent with its parent bus.
The addition is a no-op if:
1. the device being parented is not realized.
2. the device is realized, but both buses are not under reset.
Case 2 means that as long as qdev_set_parent_bus() is called
during the machine realization procedure (which is before the
machine reset so nothing is in reset), it is a no op.
There are 52 call sites of qdev_set_parent_bus(). All but one fall
into the no-op case:
+ 29 trivial calls related to virtio (in hw/{s390x,display,virtio}/
{vhost,virtio}-xxx.c) to set a vdev(or vgpu) composing device
parent bus just before realizing the same vdev(vgpu).
+ hw/core/qdev.c: when creating a device in qdev_try_create()
+ hw/core/sysbus.c: when initializing a device in the sysbus
+ hw/i386/amd_iommu.c: before realizing AMDVIState/pci
+ hw/isa/piix4.c: before realizing PIIX4State/rtc
+ hw/misc/auxbus.c: when creating an AUXBus
+ hw/misc/auxbus.c: when creating an AUXBus child
+ hw/misc/macio/macio.c: when initializing a MACIOState child
+ hw/misc/macio/macio.c: before realizing NewWorldMacIOState/pmu
+ hw/misc/macio/macio.c: before realizing NewWorldMacIOState/cuda
+ hw/net/virtio-net.c: Used for migration when using the failover
mechanism to migration a vfio-pci/net. It is
a no-op because at this point the device is
already on the bus.
+ hw/pci-host/designware.c: before realizing DesignwarePCIEHost/root
+ hw/pci-host/gpex.c: before realizing GPEXHost/root
+ hw/pci-host/prep.c: when initializaing PREPPCIState/pci_dev
typo "initializing"
+ hw/pci-host/q35.c: before realizing Q35PCIHost/mch
+ hw/pci-host/versatile.c: when initializing PCIVPBState/pci_dev
+ hw/pci-host/xilinx-pcie.c: before realizing XilinxPCIEHost/root
+ hw/s390x/event-facility.c: when creating SCLPEventFacility/
TYPE_SCLP_QUIESCE
+ hw/s390x/event-facility.c: ditto with SCLPEventFacility/
TYPE_SCLP_CPU_HOTPLUG
+ hw/s390x/sclp.c: Not trivial because it is called on a SLCPDevice
just after realizing it. Ok because at this point the destination
bus (sysbus) is not in reset; the realize step is before the
machine reset.
+ hw/sd/core.c: Not OK. Used in sdbus_reparent_card(). See below.
+ hw/ssi/ssi.c: Used to put spi slave on spi bus and connect the cs
line in ssi_auto_connect_slave(). Ok because this function is only
used in realize step in hw/ssi/aspeed_smc.ci, hw/ssi/imx_spi.c,
hw/ssi/mss-spi.c, hw/ssi/xilinx_spi.c and hw/ssi/xilinx_spips.c.
+ hw/xen/xen-legacy-backend.c: when creating a XenLegacyDevice device
+ qdev-monitor.c: in device hotplug creation procedure before realize
Note that this commit alone will have no effect, right now there is no
use of resettable API to reset anything. So a bus will never be tagged
as in-reset by this same API.
The one place where side-effect will occurs is in hw/sd/core.c in
sdbus_reparent_card(). This function is only used in the raspi machines,
including during the sysbus reset procedure. This case will be
carrefully handled when doing the multiple phase reset transition.
Signed-off-by: Damien Hedde <damien.he...@greensocs.com>
Reviewed-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Tested-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
v6 update: there are now 3 more call sites (52 instead of 49).
+ hw/isa/piix4.c
+ hw/net/virtio-net.c
+ hw/virtio/vhost-user-fs-pci.c (in list below)
Exhaustive list of the 29 "virtio" caller to qdev_set_parent_bus():
+ hw/display/virtio-gpu-pci.c: VirtIOGPUPCIBase/vgpu realize
+ hw/display/virtio-vga.c: VirtIOVGABase/vgpu realize
+ hw/s390x/vhost-vsock-ccw.c: VHostVSockCCWState/vdev realize
+ hw/s390x/virtio-ccw-9p.c: V9fsCCWState/vdev realize
+ hw/s390x/virtio-ccw-balloon.c: VirtIOBalloonCcw/vdev realize
+ hw/s390x/virtio-ccw-blk.c: VirtIOBlkCcw/vdev realize
+ hw/s390x/virtio-ccw-crypto.c: VirtIOCryptoCcw/vdev realize
+ hw/s390x/virtio-ccw-gpu.c: VirtIOGPUCcw/vdev realize
+ hw/s390x/virtio-ccw-input.c: VirtIOInputCcw/vdev realize
+ hw/s390x/virtio-ccw-net.c: VirtIONetCcw/vdev realize
+ hw/s390x/virtio-ccw-rng.c: VirtIORNGCcw/vdev realize
+ hw/s390x/virtio-ccw-scsi.c: VirtIOSCSICcw/vdev realize
+ hw/s390x/virtio-ccw-scsi.c: VHostSCSICcw/vdev realize
+ hw/s390x/virtio-ccw-serial.c: VirtioSerialCcw/vdev realize
+ hw/virtio/vhost-scsi-pci.c: VHostSCSIPCI/vdev realize
+ hw/virtio/vhost-user-blk-pci.c: VHostUserBlkPCI/vdev realize
+ hw/virtio/vhost-user-fs-pci.c: VHostUserFSPCI/vdev realize
+ hw/virtio/vhost-user-scsi-pci.c: VHostUserSCSIPCI/vdev realize
+ hw/virtio/vhost-vsock-pci.c: VHostVSockPCI/vdev realize
+ hw/virtio/virtio-9p-pci.c: V9fsPCIState/vdev realize
+ hw/virtio/virtio-balloon-pci.c: VirtIOBalloonPCI/vdev realize
+ hw/virtio/virtio-blk-pci.c: VirtIOBlkPCI/vdev realize
+ hw/virtio/virtio-crypto-pci.c: VirtIOCryptoPCI/vdev realize
+ hw/virtio/virtio-input-pci.c: VirtIOInputPCI/vdev realize
+ hw/virtio/virtio-net-pci.c: VirtIONetPCI/vdev realize
+ hw/virtio/virtio-pmem-pci.c: VirtIOPMEMPCI/vdev realize
+ hw/virtio/virtio-rng-pci.c: VirtIORngPCI/vdev realize
+ hw/virtio/virtio-scsi-pci.c: VirtIOSCSIPCI/vdev realize
+ hw/virtio/virtio-serial-pci.c: VirtIOSerialPCI/vdev realize
---
hw/core/qdev.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index d431a020fc..310b87e25a 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -96,25 +96,31 @@ static void bus_add_child(BusState *bus, DeviceState *child)
void qdev_set_parent_bus(DeviceState *dev, BusState *bus)
{
- bool replugging = dev->parent_bus != NULL;
+ BusState *old_parent_bus = dev->parent_bus;
- if (replugging) {
+ if (old_parent_bus) {
trace_qdev_update_parent_bus(dev, object_get_typename(OBJECT(dev)),
- dev->parent_bus, object_get_typename(OBJECT(dev->parent_bus)),
+ old_parent_bus, object_get_typename(OBJECT(old_parent_bus)),
OBJECT(bus), object_get_typename(OBJECT(bus)));
/*
* Keep a reference to the device while it's not plugged into
* any bus, to avoid it potentially evaporating when it is
* dereffed in bus_remove_child().
+ * Also keep the ref of the parent bus until the end, so that
+ * we can safely call resettable_change_parent() below.
*/
object_ref(OBJECT(dev));
bus_remove_child(dev->parent_bus, dev);
- object_unref(OBJECT(dev->parent_bus));
}
dev->parent_bus = bus;
object_ref(OBJECT(bus));
bus_add_child(bus, dev);
- if (replugging) {
+ if (dev->realized) {
+ resettable_change_parent(OBJECT(dev), OBJECT(bus),
+ OBJECT(old_parent_bus));
+ }
+ if (old_parent_bus) {
+ object_unref(OBJECT(old_parent_bus));
object_unref(OBJECT(dev));
}
}
